1. Field of the Invention
The invention relates to a blind arrangement for a motor vehicle, in particular for a vehicle roof.
2. Related Technology
A blind arrangement of this type is for example known from DE 10 2005 024 657 A1 and serves to shadow a transparent bodywork surface arranged, in particular, in a roof region of a vehicle. The known blind arrangement comprises a blind sheet which can be wound up on a winding tube and unwound therefrom and is guided in guide rails along its lateral edges extending in the direction of extension. For guiding in the guide rails, the blind sheet has in its edge regions in each case an edge stiffener which is formed from a metal strip, is a constant force spring and engages with a guide track of the respective guide rail. The constant force springs automatically wind up in a helical manner in a region arranged on the tail side outside the guide tracks of the guide rails. In the process, a tensile force acting in the winding-up direction is exerted on a pulling bow which extends at the front-side end of the blind sheet in the transverse direction of the vehicle and is also guided in the lateral guide rails.
A blind arrangement of the type mentioned at the outset is also known from DE 20 2005 006 415 U1. This blind arrangement also comprises a blind sheet which is provided at its external edges in each case with a helical spring. The helical springs are each guided in a guide rail arranged along a respective longitudinal edge of a roof opening of the motor vehicle in question. A winding-up aid for the blind sheet is arranged in each case on the tail side from the guide rails. The winding-up aid is in the form of a surface which is curved in the winding direction and on which the respective helical spring is guided during winding-up and unwinding of the web sheet.
In the blind arrangements according to the prior art as described hereinbefore, there is the drawback that the web sheet does not experience, in the region of the winding or the winding body, any tension in the transverse direction of the vehicle. This entails the risk in this region of a formation of folds which can become apparent on the material; this may, in turn, be visible from the interior of the vehicle in the closed position of the blind.
Furthermore, during preassembly of the blind arrangement in a motor vehicle or else in a sliding roof system, there is the problem that the blind sheet can become ruffled, in the region of its winding, inward, i.e. in the direction of the center plane of the blind arrangement. Again, this can lead to damage to the blind arrangement. In particular, the constant force spring and also the blind sheet can become damaged as a result.
A defined winding behavior is ensured in these blind arrangements by a winding core, such as a rotatably mounted winding shaft. However, components of this type are associated with additional costs and can furthermore also cause an undesirable formation of noise on actuation of the blind arrangement. Furthermore, moving components also frequently give rise to technical problems.